<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>伪元素</title>
	<style type="text/css">
		li{
			list-style: none;
		}
	li::before{content: "*"}

	</style>
</head>
<body>
<ul>
	<li>我是第一</li>
	<li>我是第二</li>
	<li>我是第三</li>
	<li>我是第四</li>
</ul>
</body>
</html>